Agricultural vehicles known as combine harvester are historically termed such because it combines multiple harvesting functions within a single harvesting unit, including picking, threshing, separating and cleaning. A combine therefore carries a header at a front end which is adapted to cut crop material from a field. The agricultural vehicle carries the header via a feeder, which is adapted to transport the crop material, removed from the field by the header, towards the body of the vehicle. In the body of the vehicle, typically, the threshing rotors are provided to perform threshing operations on the crop. Further cleaning systems are included in the body of the vehicle so that crop and residue can be optimally separated.
The present invention particularly relates to an agricultural harvester carrying a header having multiple row elements along the width of the header. Such headers are known in the art for example as corn headers or sunflower headers. Each row element comprises a feed/snapping unit. The feed/snapping unit typically includes a pair of stripper plates spaced apart from each other and extending in a forward driving direction of the agricultural vehicle carrying the header. The feed/snapping unit further comprises a pair of stalk rolls positioned underneath the stripper plates, and a pair of gathering chains for moving the stalks into the space between the stripper plates. The feed/snapping unit pulls the stem downward through the pair of stripper plates. Thereby the distance between the stripper plates is chosen such that the heads of the crop material, for example the corn heads or sunflower heads, are too large to pass through the stripper plates so that they are removed from the stalk.
Each row element further comprises a chopping unit. When the stalks are pulled downward through the stripper plates, the chopping unit chop the stalks into pieces. Thereby, it will be clear that other residue elements such as leaves are also chopped into pieces together with the stalks. These pieces are then distributed onto the field.
US 2015/0305240 describes an agricultural vehicle having a header with such set-up. In this document, it is described to separately drive the feed/snapping unit and the chopping units. By separately driving these units, the operating speed of the feed/snapping unit can be independently controlled from the operating speed of the chopping unit. Particularly the chopping units are known to consume a lot of energy. Therefore, being able to reduce the chopping unit operating speed in predetermined situations would allow a significant reduction of energy consumption.
A drawback of separately driving the feed/snapping units and the chopping units relates to the safety clutch that is typically provided between a drivetrain and the chopper units. The safety clutch is placed between each chopper unit and the drive shaft, and is adapted to slip when a threshold load is crossed by the chopper. From the agricultural vehicle cabin, operation of the feed/snapping unit can be visually controlled. In other words, an operator can see whether the feed/snapping unit is correctly operating. However, since the chopper units are located underneath the feed/snapping units, they cannot be seen from the agricultural vehicle's cabin. When the feed/snapping units are physically linked to the chopper units, a safety clutch slip can be directly visually detected by the operator since such safety clutch slip would stop both the feed/snapping unit and the chopping unit. However, when the drive system for the feed/snapping unit is separated from the drive system for the chopping unit, a safety clutch slip at the chopping unit cannot be visually detected by the operator. As a result, an operator will continue driving with a slipping safety clutch, thereby permanently damaging the safety clutch mechanism. Replacing a damaged safety clutch is cumbersome and time consuming and therefore highly costly.
It is an object of the present invention to provide a mechanism that allows early detection of clutch activation.